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| Battery test system, as for smoke detector alarm |
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| OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is illustrated an exploded view of spring ... |
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| Phase/phase/frequency-scan radar apparatus |
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| Radio controlled toy vehicle |
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| Personal alarm |
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Apparatus for identifying and tracking a targeted nuclear source
| Details |
Inventors: Godfrey, Wesley L.;
Assignee:
Primary Examiner: Swann, III; Glen R.
Assistant Examiner:
Attorney, Agent or Firm: Reynolds; Benoni O.
A plurality of fixed gamma ray detectors is deployed along a corridor or other path to be taken by a targeted nuclear source. Each fixed gamma ray detector and its associated electronics splits the spectrum of any gamma rays detected into two energy groups, one on either side of a predetermined and variable discrimination line along the energy base line. A plurality of paired single channel analyzers (dual channel analyzer), each pair collocated and electronically connected with a gamma ray detector, records the count of each portion of the detected gamma ray spectrum. A host computer computes the ratio between the radiation counts of the two energy groups on a recurring basis and compares the ratio taken on one reading of the detectors with the ratio taken on a previous reading of the detectors. An audible or visual alarm, connected to the computer, is produces when the ratio between the two energy groups has changed or has not met an expected value. To avoid simulation of the nuclear source, the coverage of the two energy groups together, in relation to the total spectrum of the detected gamma ray, or to each other, can be varied and the ratios between the upper and lower portions can be manipulated by changing the position of the discrimination line between the two energy groups. A series of the ratios obtained could be used collectively to identify the gamma emitting sample. |
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DETAILED DESCRIPTION The present invention is apparatus for identifying and tracking a targeted nuclear source usually in a manufacturing or storage facility.
It is a highly sophisticated approach to the problem of unauthorized movement of SNM (special nuclear material).
The location of such material must be monitored for personnel safety and the intrinsic value of some materials is such that they are subject to theft.
According to the preferred embodiment of this invention, the apparatus has: a detector means to detect any gamma rays emitted by readings of any nuclear source and to convert the gamma ray detected into electrical signals; an analyzing means which measures the radiation count of any gamma rays detected, electronically connected to the detector means, to split the spectrum of any gamma rays detected on either side of a predetermined and variable discrimination line into two energy groups, an upper portion and a lower portion, and to compute and compare the ratio of the radiation count of the upper portion and the radiation count of the lower portion of the gamma ray spectrum taken on one reading of the detector means with the ratio of radiation counts between the upper portion and the lower portion taken on a previous reading of the detector means or with an expected value; an alarm means, electronically connected to the analyzing means, for indicating, in a particular reading by the detector means, when the ratio of radiation counts between the two energy groups has changed or has not met an expected value.
Detector means is a plurality of fixed gamma ray detectors (crystal or proportional), each fixed gamma ray detector feeding into a photomultiplier, preamplifier and pulse amplifier, located along a corridor or other path to be taken by the targeted nuclear source.
Analyzing means is a plurality of paired single channel analyzers (also called a dual channel analyzer), deployed in close association with the detector means, each single channel analyzer having a count rate meter or counter to determine the radiation count of the upper and lower portions of the gamma ray spectrum, a host computer to determine the ratio of the radiation counts between the upper portion and the lower portion of the gamma ray spectrum and automatically compare the ratio: to another ratio taken previously, or to a library of ratios for various targeted nuclear sources, actuating an alarm means when an unexpected ratio value is detected
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